Bio-inspired self-assembly of waxberry-like core-shell SiO2@TiO2 nanoparticles towards antiglare coatings

Waxberry-like core–shell SiO₂@TiO₂ nanoparticles were prepared by liquid-phase deposition (LPD) method. The dip-coating self-assembly of waxberry-like core–shell SiO₂@TiO₂ nanoparticles has been used to fabricate coatings with excellent antiglare properties in the large angle and wide wavelength range. The field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements showed that the surface of SiO₂ nanoparticles were coated by titania as a shell with controllable and uniform thickness. The ultraviolet visible near-infrared spectrophotometer (UV-Vis-NIR) results indicate that the maximum transmittance of the antiglare coating is up to 95.80% in the visible band, whereas that of the pure glass substrate is only 92.10%. The scattering and haze of the films have been measured to show that such specifically structured coatings exhibited good antiglare properties in the large angle and wide wavelength range.

The dip-coating self-assembly of waxberry-like core–shell SiO₂@TiO₂ nanoparticles has been used to fabricate antiglare coatings with excellent antiglare properties in the large angle and wide wavelength range.     

Fabrication of superwetting,antimicrobial and conductive fibrous membranes for removing/collecting oil contaminants

In order to remove/collect organic contaminants from polluted water, polypyrrole/silver nanoparticles (PPy/Ag NPs) have been loaded onto spandex fabric using the method of in situ redox-oxidation polymerization to achieve a specific membrane. Observations showed that the original hydrophobic fabric became superhydrophilic and superoleophobic underwater (with an underwater oil contact angle (OCA) of 160°). The as-prepared specimen could effectively remove the oil from an oil-in-water emulsion. After further hydrophobic modification, the specimen was transformed into a fabric that possessed durable superhydrophobicity and superlipophilicity (with a water contact angle (WCA) of 159°), which could collect the oil from a water-in-oil emulsion. Apparently, the two types of fibrous membranes completely satisfied the conditions for removing/collecting organic contaminants from opposite types of water/oil mixtures. The durable evaluation results exhibited the outstanding resistance of both fibrous membranes to friction and acidic and basic scouring agents. Additionally, the multifunctional fabric membrane also possessed excellent electrical conductivity and antibacterial activities towards S. aureus, B. subtilis, and E. coli, which will greatly promote developments in the textile industry and provide a bright future for fabric-based materials.

In order to remove/collect organic contaminants from polluted water, polypyrrole/silver nanoparticles (PPy/Ag NPs) have been loaded onto spandex fabric using the method of in situ redox-oxidation polymerization to achieve a specific membrane.     

Insight into the synergism between MnO2 and acid sites over Mn–SiO2@TiO2 nano-cups for low-temperature selective catalytic reduction of NO with NH3

The rational synthesis of low-temperature catalysts with high catalytic activity and stability is highly desirable for the selective catalytic reduction of NO with NH₃. Here we synthesized a Mn–SiO₂/TiO₂ nano-cup catalyst via the coating of the mesoporous TiO₂ layers on SiO₂ spheres and subsequent inlay of MnO₂ nanoparticles in the narrow annulus. This catalyst exhibited superior catalytic SCR activities and stability for low-temperature selective catalytic reduction of NO with NH₃, with NO conversion of ∼100%, N₂ selectivity above 90% at a temperature ∼140 °C. The characterization results, such as BET, XRD, H₂-TPR, O₂/NH₃-TPD and XPS, indicated that this nano-cup structure catalyst possesses high concentration and dispersion of Mn⁴⁺ active species, strong chemisorbed O⁻ or O₂²⁻ species and highly stable MnO_X active components over the annular structures of the TiO₂ shell and SiO₂ sphere, and thus enhanced the low-temperature SCR performance.

A novel Mn–SiO₂@TiO₂ nano-cup catalyst with synergy of MnO₂ and acid sites for efficient low-temperature SCR reaction.     

Effect of tourmaline nanoparticles on the anticoagulation and cytotoxicity of poly(l-lactide-co-caprolactone) electrospun fibrous membranes

Tourmaline nanoparticles (TM NPs) were well dispersed in poly(l-lactide-co-caprolactone) (PLCL) fibers via electrospinning without a dispersant. Through the modification of TM NPs, the hydrophilicity and anticoagulant property of the composite electrospun fibrous membranes were improved. Compared with the PLCL membranes, the curve of dynamic clotting time in contact with the composite TM NPs/PLCL membranes descended more slowly. Particularly, the coagulation time of 8 wt% TM NPs/PLCL membrane was longer than 70 min, which was 174% higher than that of the PLCL membrane. At the same time, the cell compatibility and mechanical properties of TM NPs/PLCL membranes were analyzed. The cytotoxicity test showed that the grade of 8 wt% TM NPs/PLCL membrane was 0. The stretching experiments showed that the tensile strength of 8 wt% TM NPs/PLCL membrane (6.71 ± 0.30 MPa) was 267.33% higher than that of the PLCL membrane, and its elongation at break (141.83 ± 5.82%) was higher than the requirement of the coronary artery. These results indicated that the PLCL electrospun fibrous membranes modified with TM NPs have potential to be used in tissue engineering as small-caliber vascular grafts.

The hydrophilicity and anticoagulation of PLCL electrospun membranes were enhanced by the modification of well-dispersed TM NPs.     

Effects of NaCl treatment on the performance and environmental stability of microporous SiO2-based thin film transistors

In this letter, we report the effects of NaCl treatment on the performance and environmental stability of microporous SiO₂-based thin film transistors (TFTs). It was found that appropriate amounts of NaCl treatment significantly improved the electric double layer (EDL) capacitance of such composite solid electrolytes from 1.9 to 4.7 μF cm⁻². A highest field effect mobility of 42.8 cm² V⁻¹ s⁻¹ was found for 1% NaCl treated microporous SiO₂-based TFTs. However, 10% and 26.5% NaCl treated microporous SiO₂-based TFTs showed good environmental stability of the I_on/I_off ratio with reasonable field effect mobility.

In this letter, we report the effects of NaCl treatment on the performance and environmental stability of microporous SiO₂-based thin film transistors (TFTs).     

The pH-triggered drug release and simultaneous carrier decomposition of effervescent SiO2–drug–Na2CO3 composite nanoparticles: to improve the antitumor activity of hydrophobic drugs

To achieve a better release effect of hydrophobic drugs and spontaneous nanocarrier disintegration by dissolution as well as the CO₂ production of Na₂CO₃ further, improving the therapeutic effect of hydrophobic drugs, and thereby avoiding the accumulation of the nanocarrier in vivo to produce organ toxicity, effervescent SiO₂–drug–Na₂CO₃ composite nanoparticles (ESNs) were prepared in this study using a tetraethyl orthosilicate hydrolysis method. Sodium carbonate was used as the effervescent disintegrant to respond to the acidic microenvironment of the tumor. The properties of ESNs were assessed and TEM images were taken to verify the self-disintegration characteristics of nanocarrier materials. The in vitro anticancer efficacy of ESNs was evaluated in human breast cancer MCF-7 cells. ESNs loaded with hydrophobic drugs were successfully constructed, and showed high entrapment efficiency and drug loading. The nanocarrier successfully achieved self-disintegration in a PBS environment of pH value at 5.0, and showed excellent antitumor effect in vitro. ESNs can effectively load hydrophobic drugs and achieve self-disintegration, while avoiding toxicity from the accumulation of the nanocarrier. These results suggest that ESNs are a promising drug delivery system capable of maximizing the anticancer therapeutic efficacy and minimizing the systemic toxicity.

Effervescent SiO₂–drug–Na₂CO₃ composite nanoparticles were prepared in this study using a tetraethyl orthosilicate hydrolysis method to achieve a better release effect of hydrophobic drugs and spontaneous nanocarrier disintegration by dissolution.     

The preparation of a difunctional porous β-tricalcium phosphate scaffold with excellent compressive strength and antibacterial properties

Porous β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) scaffolds are widely applied in the field of bone tissue engineering due to their nontoxicity, degradability, biocompatibility, and osteoinductivity. However, poor compressive strength and a lack of antibacterial properties have hindered their clinical application. In order to address these disadvantages, graphene (G) and silver nanoparticles were introduced into β-TCP through a two-step method. In the synthesis process, G-β-TCP was prepared via an in situ synthesis method, and then silver nanoparticles and HAp particles were coated on the surface of the G-β-TCP scaffold in an orderly fashion using dopamine as a binder. From the results of characterization, when the content of graphene was 1 wt% of β-TCP, the G-β-TCP scaffold had the highest compression strength (127.25 MPa). And core–shell G-β-TCP-Ag-HAp not only had reduced cytotoxicity via the continuous release of Ag⁺, but it also achieved long-term antibacterial properties. Besides, the material still showed good cell activity and proliferation.

Silver nanoparticles and HAp particles were orderly coated on the surface of G-β-TCP scaffold. So the composite had good compression strength and antibacterial property.     

Synthesis and characterization of BiVO4 nanoparticles for environmental applications

In the present study, a chemical precipitation method is adopted to synthesize bismuth vanadate nanoparticles. The calcination temperature dependent photocatalytic and antibacterial activities of BiVO₄ nanoparticles are examined. The structural analysis evidences the monoclinic phase of BiVO₄ nanoparticles, where the grain size increases with calcination temperature. Interestingly, BiVO₄ nanoparticles calcined at 400 °C exhibit superior photocatalytic behaviour against methylene blue dye (K = 0.02169 min⁻¹) under natural solar irradiation, which exhibits good stability for up to three cycles. The evolution of antibacterial activity studies using a well diffusion assay suggest that the BiVO₄ nanoparticles calcined at 400 °C can act as an effective growth inhibitor of pathogenic Gram-negative (P. aeruginosa & A. baumannii) and Gram-positive bacteria (S. aureus).

In the present study, a chemical precipitation method is adopted to synthesize bismuth vanadate nanoparticles.     

Environmentally sustainable route to SiO2@Au–Ag nanocomposites for biomedical and catalytic applications

A facile, sustainable, operationally simple and mild method for the synthesis of SiO₂@Au–Ag nanocomposites (NCs) using Nephrolepis cordifolia tuber extract is described and its catalytic, antibacterial and cytotoxic properties were investigated. The fabricated SiO₂@Au–Ag NCs were well characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) to determine the optical activity, size and morphology, elemental composition, functional groups present, crystallinity, thermal stability and chemical state respectively. The obtained SiO₂@Au–Ag NCs exhibited spherical shape SiO₂ decorated with Au and Ag nanoparticles. The diameter of the SiO₂ nanoparticles ranges from 200–246 with average 3 nm diameter of Au and Ag NPs. Synthetic utility of this protocol has been demonstrated by exploring its effective catalytic activities for the solvent-free amidation of carboxylic acid with a primary amine with excellent yields. Moreover, the synthesized nanocomposite exhibited as noticeable antibacterial effect against Gram negative and Gram positive bacteria and better bio-compatibility against human keratinocytes. Thus, additive free SiO₂@Au–Ag NCs display the potential for catalysis and biomedical applications.

A facile, sustainable, operationally simple and mild method for the synthesis of SiO₂@Au–Ag nanocomposites (NCs) using Nephrolepis cordifolia tuber extract is described and its catalytic, antibacterial and cytotoxic properties were investigated.     

Design and fabrication of vapor-induced superhydrophobic surfaces obtained from polyethylene wax and silica nanoparticles in hierarchical structures

The present work reported a simple and effective approach to fabricate a low-cost, self-cleaning and mechanically durable superhydrophobic coating. The coating was prepared by dip-coating certain substrates in an ethyl acetate suspension of silica nanoparticles (SiO₂), hydroxyl acrylic resin, cross-linking agent and polyethylene wax (PEW). Through the control of the cooling and drying process, vapor-induced PEW micro-clusters were formed on the surfaces during the evaporation of ethyl acetate, and uniform carpet-like hierarchical structures were finally obtained by properly adjusting the dosage of PEW. Under the synergistic effect of hydrophobic SiO₂ nanoparticles and PEW micro-clusters, the composite coating exhibited a remarkable superhydrophobicity with a contact angle of 163° ± 5° with 25 wt% content of PEW, as well as preeminent self-cleaning properties against various food liquids. Moreover, the coating still maintained its surface cleanliness when immersed in the cyclohexane or hexadecane, indicating a superior self-cleaning property against solvent-contamination. The mechanical durability test showed that the coating still kept its excellent water repellency after fairly intensive knife-scratching, tape peeling and 25 cycles of sandpaper abrasion under 100 g of loading, indicating a quite admirable mechanical durability. The facile preparation and high-performance of the coating make it quite suitable for manufacture on a large scale, which is favorable for the development of superhydrophobic coatings.

Fabrication of superhydrophobic surfaces based on PEW and SiO₂ though a vapor-induced method.     

Ag decorated silica nanostructures for surface plasmon enhanced photocatalysis

In this article, we present a novel synthesis of mesoporous SiO₂/Ag nanostructures for dye (methylene blue) adsorption and surface plasmon mediated photocatalysis. Mesoporous SiO₂ nanoparticles with a pore size of 3.2 nm were synthesized using cetyltrimethylammonium bromide as a structure directing agent and functionalized with (3-aminopropyl)trimethoxysilane to introduce amine groups. The adsorption behavior of non-porous SiO₂ nanoparticles was compared with that of the mesoporous silica nanoparticles. The large surface area and higher porosity of mesoporous SiO₂ facilitated better adsorption of the dye as compared to the non-porous silica. Ag decorated SiO₂ nanoparticles were synthesized by attaching silver (Ag) nanoparticles of different morphologies, i.e. spherical and triangular, on amine functionalized silica. The photocatalytic activity of the mesoporous SiO₂/Ag was compared with that of non-porous SiO₂/Ag nanoparticles and pristine Ag nanoparticles. Mesoporous SiO₂ nanoparticles (k_d = 31.3 × 10⁻³ g mg⁻¹ min⁻¹) showed remarkable improvement in the rate of degradation of methylene blue as compared to non-porous SiO₂ (k_d = 25.1 × 10⁻³ g mg⁻¹ min⁻¹) and pristine Ag nanoparticles (k_d = 19.3 × 10⁻³ g mg⁻¹ min⁻¹). Blue Ag nanoparticles, owing to their better charge carrier generation and enhanced surface plasmon resonance, exhibited superior photocatalysis performance as compared to yellow Ag nanoparticles in all nanostructures.

In this article, we present a novel synthesis of mesoporous SiO₂/Ag nanostructures for dye (methylene blue) adsorption and surface plasmon mediated photocatalysis.     

The fabrication of mechanically durable and stretchable superhydrophobic PDMS/SiO2 composite film

Stretchable superhydrophobic film was fabricated by casting silicone rubber polydimethylsiloxane (PDMS) on a SiO₂ nanoparticle-decorated template and subsequent stripping. PDMS endowed the resulting surface with excellent flexibility and stretchability. The use of nanoparticles contributed to the sustained roughening of the surface, even under large strain, offering mechanically durable superhydrophobicity. The resulting composite film could maintain its superhydrophobicity (water contact angle ≈ 161° and sliding angle close to 0°) under a large stretching strain of up to 100% and could withstand 500 stretching–releasing cycles without losing its superhydrophobic properties. Furthermore, the obtained film was resistant to long term exposure to different pH solutions and ultraviolet light irradiation, as well as to manual destruction, sandpaper abrasion, and weight pressing.

Stretchable superhydrophobic film was fabricated by casting silicone rubber polydimethylsiloxane (PDMS) on a SiO₂ nanoparticle-decorated template and subsequent stripping.     

Turning over on sticky balls: preparation and catalytic studies of surface-functionalized TiO2 nanoparticles

We have investigated the reactivity of rhodium(iii) complex-functionalized TiO₂ nanoparticles and demonstrate a proof-of-principle study of their catalytic activity in an alcohol oxidation carried out under aqueous conditions water in air. TiO₂ nanoparticles (NPs) have been treated with (4-([2,2′:6′,2′′-terpyridin]-4′-yl)phenyl)phosphonic acid, 1, to give the functionalized NPs (1)@TiO₂. Reaction between (1)@TiO₂ NPs and either RhCl₃·3H₂O or [Rh₂(μ-OAc)₄(H₂O)₂] produced the rhodium(iii) complex-functionalized NPs Rh(1)₂@TiO₂. The functionalized NPs were characterized using thermogravimetric analysis (TGA), matrix-assisted laser desorption ionization (MALDI) mass spectrometry, ¹H NMR and FT-IR spectroscopies; the single crystal structures of [Rh(1)₂][NO₃]₃·1.25[H₃O][NO₃]·2.75H₂O and of a phosphonate ester derivative were determined. ¹H NMR spectroscopy was used to follow the reaction kinetics and to assess the recyclability of the NP-supported catalyst. The catalytic activity of the Rh(1)₂@TiO₂ NPs was compared to that of a homogeneous system containing [Rh(1)₂]³⁺, confirming that no catalytic activity was lost upon surface-binding. Rh(1)₂@TiO₂ NPs were able to withstand reaction temperatures of up to 100 °C for 24 days without degradation.

A proof-of-principle investigation of the reactivity of functionalized NPs Rh(1)₂@TiO₂ (1 = (4-([2,2′:6′,2′′-terpyridin]-4′-yl)phenyl)phosphonic acid, 1) is reported, using their catalytic activity in an alcohol oxidation in aqueous conditions water.     

Assessing the potential biological activities of TiO2 and Cu,Ni and Cr doped TiO2 nanoparticles

Nanoparticles are like magic bullets and nanomaterials exhibit appealing properties. Their size and morphology can be switched by dopants for certain biological activities. Nanoparticles in combination with certain drugs enhance the antibiotic effects and may be valuable in combating bacterial resistance. The antimicrobial potency of nanoparticles depends upon their ability to bind to the surface of microbial cell membranes resulting in modulation of basic cell functions such as respiration. We report herein the antibacterial, antifungal and antioxidant activities of pure TiO₂ and TiO₂ doped with 4% Cu, Ni and Cr. The performance of pure and doped nanoparticles has been compared with reference compounds. A comparison of the antifungal activities of the samples doped with TiO₂ reveals that Cu–TiO₂ exhibits improved performance against A. fumigatus but lower antifungal activity against Mucor sp. and F. solani. Cu–TiO₂ and Ni–TiO₂ showed good antibacterial action against B. bronchiseptica, while Cr–TiO₂ nanoparticles displayed better activity against S. typhimurium as compared to pure TiO₂. Moreover, pristine TiO₂ and Ni–TiO₂ nanoparticles were found to demonstrate maximum total antioxidant capacity.

Nanoparticles bind to the surface of the cell membranes of microbes altering their basic cell functions and resulting in cell death.     

Electroless deposition of RuO2-based nanoparticles for energy conversion applications

This study reports a delicate electroless approach for the deposition of RuO₂·nH₂O nanoparticles on the VO_x·mH₂O nanowires and this method can be extended to deposit RuO₂·nH₂O nanoparticles on various material surfaces. Electrochemical characterizations, including linear sweep voltammetry (LSV), electrochemical quartz crystal microbalance (QCM) analysis and rotating ring-disc electrode (RRDE) voltammetry, were carried out to investigate the growth mechanism. The deposition involves the catalytic reduction of dissolved oxygen by the V⁴⁺ species of VO_x·mH₂O, which drives the oxidation of RuCl₃ to proceed with the growth of RuO₂·nH₂O. This core/shell VO_x·mH₂O/RuO₂·nH₂O shows a better catalytic activity of the oxygen reduction reaction (ORR) than RuO₂·nH₂O, which is ascribed to the pronounced dispersion of RuO₂·nH₂O. Such an electroless approach was applicable to the preparation of a RuO₂-based nanoparticle suspension as well as the deposition of nanocrystalline RuO₂·nH₂O on other functional supports like TiO₂ nanowires. The thus-obtained RuO₂-decorated TiO₂ nanorods exhibit significantly an enhanced photoactivity toward photoelectrochemical water oxidation. The versatility of the current electroless approach may facilitate the widespread deployment of nanocrystalline RuO₂·nH₂O in a variety of energy-related applications.

The core/shell VO_x·mH₂O/RuO₂·nH₂O, synthesized by simply immersing VOx·mH₂O into RuCl₃ solution, shows a better catalytic activity of ORR than RuO₂·nH₂O.     

Fabrication of a blood compatible composite membrane from chitosan nanoparticles,ethyl cellulose and bacterial cellulose sulfate

A heparin-like composite membrane was fabricated through electrospinning chitosan nanoparticles (CN) together with an ethylcellulose (EC) ethanol solution onto a bacterial cellulose sulfate membrane (BCS). Scanning electron microscopy images revealed that there were no chitosan particles in the obtained composite CN-EC/BCS membranes (CEB), indicating CN had been stretched to nanofibers. X-ray photoelectron spectroscopy verified the existence of –NH₂ from chitosan and –SO₃⁻ from BCS on the surface of CEB membranes. Positively charged CN in the electrospinning solution and negatively charged BCS on the collector increased the electrostatic force and the electrospinning ability of the EC was increased. The membrane was hydrophobic, with a water contact angle higher than 120°. CEB membranes expressed good blood compatibility according to the results of coagulation time and platelet adhesion experiments. No platelets adhered on the surface of the CEB membranes. An inflammatory response was investigated according to activation of the macrophages seeded onto the membranes. Macrophages seeded on CEB membranes are not activated after 24 h incubation.

A blood compatible membrane was fabricated through electrospinning a solution of chitosan nanoparticles and ethylcellulose onto a bacterial cellulose sulfate membrane to mimic heparin''s structure.     

Preparation of SiO2@TiO2:Eu3+@TiO2 core double-shell microspheres for photodegradation of polyacrylamide

Recently, polyacrylamide (PAM) has been widely used in polymer flooding technology to enhance oil recovery and oil production. However, the difficulty in removing hydrolysed PAM (HPAM) from wastewater still seriously blocks the further application of polymer flooding in the oilfields. Herein, we demonstrate the preparation of SiO₂@TiO₂:Eu³⁺@TiO₂ core double-shell microspheres (STT) through a two-step solvothermal and sol–gel coating strategy. The as-prepared STT exhibits an ideal photocatalytic activity for the photodegradation of HPAM. More importantly, by using STT as the model, the correlation between fluorescence intensity and photocatalytic activity of the photocatalysts is investigated. The results suggest their oppositional relationship. Since many kinds of photocatalysts are utilized in the degradation of organic pollutants, it is believed that our work will not only promote the development of photocatalysis in the field of oil extraction, but also offer a convenient method for evaluating the photocatalytic activity of the photocatalysts.

SiO₂@TiO₂:Eu³⁺@TiO₂ core double-shell microspheres with an ideal photocatalytic activity are designed and prepared for photodegradation of HPAM.     

Li4SiO4 Doped-Li7P2S8I solid electrolytes with high lithium stability synthesised using liquid-phase shaking

In this study, mechanical milling and liquid-phase shaking are used to synthesise 3Li₂S·P₂S₅ LiI·xLi₄SiO₄ (Li₇P₂S₈I·xLi₄SiO₄) solid electrolytes. When mechanical milling is used, the electrolyte samples doped with 10 mol% of Li₄SiO₄ (Li₇P₂S₈I·10Li₄SiO₄) have the highest ionic conductivity at ∼25–130 °C. When liquid-phase shaking is used, they exhibit a relatively high conductivity of 0.85 mS cm⁻¹ at ∼20 °C, and low activation energy for conduction of 17 kJ mol⁻¹. A cyclic voltammogram shows that there are no redox peaks between −0.3 and +10 V, other than the main peaks near 0 V (v.s. Li/Li⁺), indicating a wide electrochemical window. The galvanostatic cycling test results demonstrate that the Li₇P₂S₈I·10Li₄SiO₄ has excellent long-term cycling stability in excess of 680 cycles (1370 h), indicating that it is highly compatible with Li. Thus, Li₇P₂S₈I solid electrolytes doped with Li₄SiO₄ are synthesised using the liquid-phase shaking method for the first time and achieve a high ionic conductivity of 0.85 mS cm⁻¹ at 25 °C. This work demonstrates the effects of Li₄SiO₄ doping, which can be used to improve the ionic conductivity and stability against Li anodes with Li₇P₂S₈I solid electrolytes.

The galvanostatic cycling test results demonstrate that the Li₇P₂S₈I·10Li₄SiO₄ has excellent long-term cycling stability in excess of 680 cycles (1370 h), indicating that it is highly compatible with Li anode.     

A citric acid-assisted deposition strategy to synthesize mesoporous SiO2-confined highly dispersed LaMnO3 perovskite nanoparticles for n-butylamine catalytic oxidation

Catalytic oxidation can efficiently eliminate nitrogen-containing volatile organic compounds (NVOCs) and suppress the generation of toxic NO_x in order to avoid secondary pollution. In this study, mesoporous SiO₂-confined LaMnO₃ perovskite nanoparticles with high dispersion were successfully prepared by a citric acid-assisted deposition method (LMO/SiO₂-SD) and tested for the oxidation of n-butylamine. The method utilized the synergistic effect of abundant active hydroxyl groups existing on the SiO₂ gel surface and citric acid, rendering the metal ions more uniformly scattered on the SiO₂ surface. Strikingly, the LMO/SiO₂-SD sample exhibited the optimum catalytic performance (T₉₀ at 246 °C) and the highest N₂ selectivity, which was mainly ascribed to its abundant surface acid sites, superior low-temperature reducibility and higher ratio of surface Mn⁴⁺ species. The apparent activation energy (E_a) for n-butylamine oxidation over LMO/SiO₂-SD sample was 29.0 kJ mol⁻¹. Furthermore, the reaction mechanism of n-butylamine oxidation was investigated by in situ FITR and a reasonable reaction route for n-butylamine oxidation over the LMO/SiO₂-SD sample was proposed.

A citric acid-assisted deposition strategy was applied to synthesize mesoporous SiO₂-confined highly dispersed LaMnO₃ perovskite nanoparticles with optimum catalytic performance and N₂ selectivity.     

Electrospinning preparation and near-infrared absorption properties of a silica/cesium tungsten bronze micro–nano fiber membrane

Silica/cesium tungsten bronze (SiO₂/Cs_xWO₃) composite micro–nano fiber membranes were prepared by the co-precursor electrostatic spinning method using cesium chloride, tungsten powder and tetraethyl orthosilicate as raw materials. TGA, XRD, FT-IR, XPS, SEM and ultraviolet-visible-near red spectrophotometry were used to analyze the thermal decomposition process, phase composition, microscopic morphology and near-infrared absorption properties of the product. Studies have shown that as the ratio of Cs/W of raw materials increases, the crystallinity of Cs_xWO₃ in the product increases first and then decreases. When n(Cs)/n(W) reaches 0.5, its crystallinity is the most complete; similarly, calcination also contributes to the crystallization of Cs_0.33WO₃, but high temperatures above 800 °C will also destroy its crystal structure. The study found that after calcination at 700 °C, the fiber membrane with a Cs/W atomic ratio of 0.5 has the best infrared absorption performance. The average absorbance of near-infrared light at 780–2500 nm is 1.5, which is 5.56 times that of the pure SiO₂ fiber membrane. The tensile strength reaches 2.4 MPa, which can meet practical requirements. This research provides a basis for the development of flexible solar shading materials under complex outdoor conditions.

A silica/cesium tungsten bronze composite fiber membrane with good near-infrared shielding performance is prepared by electrostatic spinning, and can be used for solar heat insulation.